Aggressive female beagle, sometimes

Question
I started out with one beagle, the one I am having a problem with.  At a year old, I introduced an elder male beagle which they ended up having a litter together.  I kept one of the puppies, a male.  The mother and son have always played aggressively together, but have always been playful.  When the puppy was 3 months, I rescued a female beagle to pair with the puppy.  All was fine for quite a while.  Within the past year, the original female has gotten aggressive towards the new female, when I give any attention to the new female, it sets off the original female.  The other day, I took the original female to the dog park, hoping that she would bond with me and feel "special".  When we returned, she got aggressive towards the new female.  I have to hold her and stay with her, making her sit until she calms down.  Today, the original female and her son were playing rough, and they often begin to "gang up" on the new female.  I picked up the new female and carried her to the other side of the area, and as soon as I put her down, the original female went off and wants to fight.  She only wants to fight with the new female, she is never aggressive with the males, only playfully aggressive with the males.  They are fine together "most" of the time, when left alone.  When I am around, or there is food, the aggressiveness changes and she raises her hackle and I have been bitten a couple times, once today, trying to calm her.  A month ago, I tried keeping them together with me at all times, when the new female was finishing her heat, as I kept the new female in the house while she was in heat, and needed to reintroduce her to the pack.  "Most" of the time, they were fine together, but as soon as I gave them a treat, the aggressive behavior returned.  I feed them all together and they are usually fine, I have taught them not to eat out of each others dishes.  It's only when they are together and I give them treats, they fight.  If I give them bones, they each go in different directions, but they are fine.  I haven't sought help from a trainer yet, and would like suggestions on finding a knowledgeable trainer.  Thanks.  I live in Hawaii, so the dogs are outside most of the time, I only bring them in when they are in heat, the males remain outside year round.

Answer
Hi thanks for reaching out for help and writing to me..... you have some major and dangerous issues going on. First off with that many dogs you have pack dynamics happening and I am not sure you understand how that all works, as well you need to be the Alpha but it doesnt look like that is the case as the females are now vying for who is in charge. Then to top it off you have not spayed or neutered anyone so the hormones are raging. In addition, This sentence = "I have to hold her and stay with her, making her sit until she calms down."  is very concerning to me because you are reinforcing this behavior by doing that. Lastly you are reporting food aggression amongst them. This is not a healthy well balanced pack. YOU NEED IMMEDIATE ITNERVENTION FROM A QUALIFIED TRAINER THAT CAN COME TO YOUR HOUSE!!!!!!! The aggression is going to escalate and someone is going to get really hurt, the fact that you have been bitten in the middle of all this tells me the level of aggression going on, they do not mean to bite you but if they are extremely aggressive you can accidently get bit. NEVER....I MEAN NEVER.... put your hands in the middle of two dogs fighting. Throw a shake can at them, turn the hose on them or if you can safly grab a collar lift one away and to a separate room for at least 30 minutes and even then when they come back together you must be vigilant. These dogs should NOT be fed together and you must always remain in the middle to avert anything happening.

To find a trainer you can go to http://www.apdt.com/ which is the website for association of pet dog trainers or to http://www.nadoi.org/ which is a national organization for trainers. You should be able to find someone reliable through those sites and please..... do it quickly before someone ends up ripped to shreds or dead. These dogs need to be fixed as well.